In a portable telephone, a PDA, a pocket PC and the like which are portable equipments, an equipment comprising a first casing provided with a keyboard and the like on the upper surface, a second casing provided with a display and the like on the upper surface, and further a slide mechanism is already marketed, wherein the slide mechanism realizes a closed state, in which the first casing and the second casing overlap each other so as to cover the upper surface of the first casing with the second casing, and the slide mechanism realizes by sliding the second casing with regard to the first an opened state, in which the upper surface of the first casing is exposed. As such a portable equipment, the one disclosed in JP Laid-open patent application No. 2007-267238 is already known. The portable equipment described in this Laid-open patent application is, although not shown in the drawings in details, equipped with a slide mechanism which realizes, by relatively sliding in a short side direction the first and second casings, both having substantially a rectangular shape in a plan view, the closed state in which the first casing and the second casing overlap each other so that the upper surface of the first casing is covered with the second casing, and further realizes, by sliding second casing with regard to the first casing, the opened state, in which the upper surface of the first casing is exposed.
A slide mechanism disclosed in this Laid-open patent application is so designed that a first casing and a second casing are slidable with regard to each other by slidably engaging a slider member attached to the second casing with engagement portions provided on both sides of a base member attached to the first casing. Since a load is thus applied to the engagement portions on the both sides of the base member as engaged with the slider member, in sliding the second casing so that the upper surface of the first casing is exposed, an engagement length should be long between the base member and the slider member so as to assure a resistance for supporting the load. If an engagement length is designed to be long in this manner between the base member and the slider member, a dead area in which the casings partially overlap each other extends in a large area, so that a space on the upper surface of the first casing in particular can not be effectively used. In case of such an extended dead area, there is a problem of a reduced key space, and a further problem in that, in order to avoid this, a size of a portable equipment, and in a short side direction in particular must be extended.
Moreover, in case that a portable equipment having a large dead area is provided with springs being urging members between a base member and a slider member so as to realize a slide movement of the slider member with regard to the base member, a space for mounting a spring is inevitably narrow, so that springs are exposed to the outside, and to avoid this, there is a problem in that arrangement and settings of springs are restricted.